The present invention relates generally to biocompatible fasteners and more particularly to impermanent biocompatible fasteners.
Biocompatible fasteners have long been used to fasten together two or more biological materials on or within a patient. Examples of biocompatible fasteners include sutures, staples, surgical glues, tissue clips and orthopedic fixation devices, such as bone plates, screws and the like. For certain applications, such as where the biocompatible fastener is implanted within a patient and is needed therewithin for only a limited period of time, it is highly desirable that the biocompatible fastener be impermanent or capable of degrading over time so that an additional medical procedure not be required to remove the fastener from the patient. For this reason, many biocompatible fasteners now in use are made entirely out of materials that, over time, become chemically degraded within a patient and, ultimately, are fully metabolized and excreted by the patient. (Other biocompatible fasteners are made out of materials that the body needs and are not excreted.) Such impermanent biocompatible fasteners are typically referred to in the art as bioabsorbable fasteners and are made out of materials including, but not limited to, homopolymers and copolymers of glycolide, lactide, ε-caprolactone and p-dioxanone, copolymers of glycolide and trimethylene carbonate, as well as polyanhydrides and polyorthoesters. See Middleton et al., “Synthetic Biodegradable Polymers as Medical Devices,” Medical Plastics and Biomaterials (March 1998), the disclosure of which is incorporated herein by reference.
Gastroesphageal reflux disease (GERD) is a disorder in which the lower esophageal sphincter, which is located in a distal portion of the esophagus adjacent to the junction between the esophagus and the stomach, allows contents of the stomach, including gastric acid and bile, to reverse flow into the distal portion of the esophagus during digestion. Complications associated with GERD include heartburn, pulmonary disorders, chest pain, esophageal ulcers, esophagitis, Barrett's esophagus, and esophageal carcinoma.
Although weight loss and/or prescription acid blockers are typically preferred treatment options for GERD, various surgical procedures have been devised to treat GERD where weight loss and/or prescription drugs are ineffective or impractical. In one surgical procedure, known as Nissen fundoplication, a portion of the gastric fundus of the stomach is wrapped around the esophagus and is secured thereto using one or more biocompatible fasteners, typically in the form of sutures, surgical staples or surgical two-part fasteners. The wrapped gastric fundus applies pressure to the esophagus in such a way as to eliminate the reverse flow of stomach contents into the esophagus.
One of the more commonly used fundoplication procedures requires abdominal or thoracic incisions through which the fundus wrapping and securing can be performed. Due to the highly invasive nature of such surgery, complications and morbidity occur in a significant percentage of cases. In addition, these procedures are time-consuming, often taking a number of hours to perform, and may leave disfiguring scars where the incisions were made.
More recently developed fundoplication procedures limit somewhat the necessity of making large surgical incisions by utilizing laproscopic ports or percutaneous endoscopic gastrostomy. Although these procedures are less invasive than those involving large abdominal and thoracic incisions, they are still invasive and have certain risks associated therewith. For example, general anaesthesia, which entails well-known risks, is typically used during these procedures.
An even more recently developed fundoplication procedure is endoluminal fundoplication. In endoluminal fundoplication, a flexible endoscope is passed first through a patient's mouth and then through the esophagus to locate an attachment site at the gastroesophageal junction. A tissue grasping device is then positioned at the distal end of the endoscope and is attached to the located attachment site. Next, a tissue displacement device is positioned at the distal end of the endoscope and is used to displace the fundus of the stomach in such a way as to create an intussusception of the esophagus into the gastric lumen. A fastener delivery device is then used to secure the gastric fundus to the esophagus at a first location. The fastener delivery device is then used to place additional fasteners at a plurality of additional desired fastener locations, thus securing the gastric fundus entirely around the esophagus.
Examples of endoluminal fundoplication procedures are disclosed in U.S. Pat. No. 6,086,600, inventor Kortenbach, which issued Jul. 11, 2000, and in U.S. Pat. No. 6,113,609, inventor Adams, which issued Sep. 5, 2000, both of which are incorporated herein by reference.
In the aforementioned U.S. Pat. No. 6,113,609, there is disclosed a fundoplication fastener that is made entirely out of a bioabsorbable material. One problem that has been noted by the present inventors is that, whereas a fundoplication fastener need only be capable of securing the gastric fundus to the esophagus for the approximately three- to six-month period of time necessary for the gastric fundus and the esophagus to become fused to one another, a bioabsorbable fundoplication fastener typically will remain in place for approximately two years before chemical degradation results in its structural decay.